BEIJING - First there were 20,000 dead pigs floating down the Huangpu River, a main source of water for Shanghai. That was followed by thousands of dead ducks in the Nanhe River in the southwest province of Sichuan.

Now the Ministry of Public Safety says today online that it has apprehended meat traders in eastern China who were passing rat off as lamb. The police took in 63 suspects accused in selling more than $1.6 million of rat as lamb.

Outrage on microblog Weibo questioned how such big business could be done without raising alarm bells.

Meat smuggling and food adulteration is rampant in China. In this case, the suspects are accused of using gelatin, red pigment and nitrates to alter the rat.

As Mao Shaolong, a professor at Remnin University in Beijing, told The New York Times, "Chinese food production has become larger scale and more technological, but the problems emerging also involve using more sophisticated technology to beat regulators and cheat customers."

Shanghai police have posted a lengthy explanation for how consumers can tell the difference between rat and lamb.

Tainted meats are an ongoing problem here. A consumer in Shaanxi province reportedly died after eating lamb doused in pesticide.

China's government says it is making food safety a top priority in the first year of new president Xi Jinping's leadership.